Biological materials have been extracted from raw material of animal origin, such as pig eye sclera, by treatment with alkali and acetic acid solutions as shown in Soviet Inventor's Certificate No. 1747075, Cl. A 61 K 37/12. The material synthesized by this prior art method can be used in ophthalmological applications only after very lengthy and complex treatment. The material is characterized by extremely high solubility and low enzyme resistance. Hence, the material is not suitable for use in ophthalmology.